Arrieta will wear uniform number 49 and start the second game of today's twinbill.

The 27-year-old Arrieta was acquired by the Cubs from Baltimore as part of the deal that sent right-handed pitcher Scott Feldman to the Orioles on July 2. Arrieta reported to Iowa and is 1-2 with a 4.03 ERA (10 ER/22.1 IP) in five starts with Chicago's Triple-A affiliate.

Arrieta is 20-25 with a 5.46 ERA (217 ER/358.0 IP) in 69 major league appearances, all but six as a starting pitcher, in all or part of the last four seasons with Baltimore (2010-13). He was originally selected by the Orioles in the fifth round of the 2007 Draft and made his major league debut in 2010 at the age of 24. He was a 10-game winner for the Orioles the next season in 2011, going 10-8 with a 5.05 ERA (67 ER/119.1 IP) in 22 starts. Arrieta has split the last two seasons (2012-13) between Baltimore and Triple-A Norfolk.

The 6-foot-4, 225-pound Arrieta was Baltimore's Opening Day starter in 2012 and a member of Baltimore's Opening Day roster this year. In 2013, he had three stints with the Orioles, going 1-2 with a 7.23 ERA (19 ER/23.2 IP) in five starts. With Norfolk, Arrieta went 5-3 with a 4.41 ERA (24 ER/49.0 IP) in nine appearances (eight starts) this year.

Arrieta was drafted by the Orioles out of Texas Christian University and made his professional debut in 2008. A year later, he advanced as high as Triple-A, going 11-11 with a 3.40 ERA (57 ER/150.2 IP) in 28 starts between Double-A Bowie and Norfolk. He began the 2010 campaign going 6-2 with a 1.85 ERA (15 ER/73.0 IP) in 12 appearances (11 starts) with Norfolk to earn his first promotion to the big leagues.